Currently in airplanes and trains, because of space limitation, the back of seats cannot lie down, other than in premium classes of travel. Passengers therefore have to sit vertically or almost vertically for a long time, or even sleep in the vertical or near-vertical sitting position. In the vertical sitting position, the waist, spine and neck can easily get tired because they have to support the whole weight of the upper body and head. During sleep, there is lack of support, the position of the body is unstable, resulting in muscle pain, strain and paralysis.
Many prior art inventions, such as those found in the references cited below, offer methods and devices to remove some of the load caused by a long stay in an upright position.
The state of the art in the field is believed to be represented by the following U.S. Pat. Nos. 6,266,825, 6,007,156, 4,996,978, 4,834,457, 4,788,969, 3,827,716, 3,612,605, 3,531,158, 3,524,679, 3,191,599, 3,099,486, 3,063,752, 3,004,794, 2,851,033, 2,667,917, 2,667,913, 2,255,464, 1,722,205 and 284,024.
None of these inventions has yet materialized into a functional solution to the problem, possibly because the solution offered is either partial or inconvenient to use. For example, in U.S. Pat. No. 6,007,156 to G. H. Chang for “Vertical Rest Helping Method and Apparatus”, there is described a device that fixes the passenger in a predetermined position, which is not necessarily the subjective optimal position as determined by the user, and without the simple ability to change posture from time to time, or to leave and return to the seat when desired, to subjectively adjust the sitting position for user comfort, or reach the user's pockets or clothing. Furthermore, the solution proposed may impair passenger safety by fixing the passenger to his seat and reducing his evacuation speed in dangerous situations.
There therefore exists a need to provide a device and method for assisting passengers to sleep in an upright position, but which overcomes at least some of the disadvantages of prior art devices and methods.
The disclosures of each of the publications mentioned in this section and in other sections of the specification are hereby incorporated by reference, each in its entirety.